PageSetup.PaperSize

public PaperSizeType PaperSize { get; set; }

using System;
using Aspose.Cells;

namespace AsposeCellsExamples
{
    public class PageSetupPropertyPaperSizeDemo
    {
        public static void Run()
        {
            // Create a new workbook
            Workbook workbook = new Workbook();
            Worksheet sheet = workbook.Worksheets[0];

            // Set the paper size to Envelope B6
            sheet.PageSetup.PaperSize = PaperSizeType.PaperEnvelopeB6;

            // Print the current paper size
            Console.WriteLine("Current paper size: " + sheet.PageSetup.PaperSize);

            // Save the workbook
            workbook.Save("PageSetup_PaperSizeDemo.xlsx");
        }
    }
}